Uninflammable insulating liquid

Abstract

An uninflammable insulating liquid is obtained by adding an emulsifying agent having a volume ratio of 1 to 3% to an insulating liquid containing a fluorocarbon liquid of at least 25% in a volume ratio to cause emulsification. In this liquid mixture, when polyol ester or polydimethylsiloxane is used as the insulating liquid, an uninflammable insulating liquid that does not cause pollution or an environmental problem can be obtained. When tricresyl phosphate is used as the insulating liquid, an uninflammable insulating liquid having a dielectric constant close to that of insulating paper can be obtained. A liquid pipe for circulating a fluorocarbon emulsion in a tank is provided outside the tank, and a pump and a stirrer are connected midway along the liquid pipe to constantly stir the fluorocarbon emulsion, thereby preventing it from being separated into two layers. When a radiator is provided to the liquid pipe, the stirring system for the fluorocarbon emulsion can also serve as the cooling system.

What is claimed is: 
     
       1. An uninflammable insulating liquid comprising a mixture of a polyol ester and a perfluoropolyether, wherein the perfluoropolyether is present in an amount of at least 25 volume percent, and also wherein the mixture of the polyol ester and the perfluoropolyether is emulsified by the addition of an emulsifier selected from the group consisting of stearic acid and a combination of stearic acid and a derivative of a perfluoropolyether obtained by introducing a carboxyl group or a hydroxyl group to the terminal of the perfluoropolyether, which is added to the mixture of the polyol ester and the perfluoropolyether in an amount of 1 to 3 volume percent. 
     
     
       2. An uninflammable insulating liquid comprising a mixture of a dimethylpolysiloxane silicone oil and a perfluoropolyether, wherein the perfluoropolyether is present in an amount of at least 25 volume percent, and also wherein the mixture of the dimethylpolysiloxane silicone oil and the perfluoropolyether is emulsified by the addition of an emulsifier selected from the group consisting of stearic acid and a combination of stearic acid and a derivative of a perfluoropolyether obtained by introducing a carboxyl group or a hydroxyl group to the terminal of the perfluoropolyether, which is added to the mixture of the dimethylpolysiloxane silicone oil and the perfluoropolyether in an amount of 1 to 3 volume percent. 
     
     
       3. An uninflammable insulating liquid comprising a mixture of a tricresyl phosphate and a perfluoropolyether, wherein the perfluoropolyether is present in an amount of at least 25 volume percent, and also wherein the mixture of the tricresyl phosphate and the perfluoropolyether is emulsified by the addition of an emulsifier selected from the group consisting of stearic acid and a combination of stearic acid and a derivative of a perfluoropolyether obtained by introducing a carboxyl group or a hydroxyl group to the terminal of the perfluoropolyether, which is added to the mixture of the tricresyl phosphate and the perfluoropolyether in an amount of 1 to 3 volume percent.